Im looking to get a new exhaust on my 04 silverado and was wondering what style gets the best performance gains.

1. One in Duel out
2. Duel in Duel out
3. or true duels

 

You will get the most power with dual exhaust hands down, but you can also just get a performancemuffler and a high flow catto replace the stock one and you'll make more power for a little less money!

 

I'm running flow master 40's and loving them for the past 5 years.

 

Well it depends true duels and regular spit dual (likeafter the muffler) both will increase your mileage and both will increase power. Thetrue dual will give a slight hpbump but its going to boil down to emissions (if you have to get tested and does yourlaw will allow it) some states say you can't replace the factory converter unless there is a failure, althoughsome don't. Some once you cut the factory type system (the y-pipe and the cat) and change the position or modify the design you will not pass the standard. You could also ditch the y-pipe and use an x-pipe and run the pipe out the back if you wanted.Now that being said there are a couple of ways that you can change, still be legal and have more power as well as sound. My buddy has a 2000 Silverado Z71 with the 5.3 and what I did was I took the cat and replaced with a high flow cat (which in our state its legal) then we split the exhaust about 1.5 feet behind the cat and run two separate pipes all the way back running the drivers side all the way back until it would clear the driveshaft with no problems them angled both pipes out to the corners of the bedwith ashort (I think 12-16") glasspack in each pipe about 12" from the axle Although we just recently went back to the glasspacks. We didn't have mufflers on it but it sounded bad and I talked himinto goin back toglasspacks and it didn't really quiet it down (IMO) just changed the tone to one thatsmore bareable.All of the piping is 2.5"which is perfect.We did tune the truck with a hypertech tune. Athough I seen guys do this without messing with the tune. The only other modification aside fromsuspension and tires is aCAI (Cold Air Intake Kit). You coulduse a flowmaster, magnaflow, with the exhaustsplit behind the muffler it boils down to how loud you want the truck really and personal preference. Everybody has their own opinion on exhaust.
Here is a new clip I found off of you tube that is the closest I could find to his truck. I postedone on another site but this one is better and closer to the sound.
(THISIS NOT HIS TRUCK BUT IT IS REAL CLOSE). I posted this to give you an idea of the sound.
Hope this helps and gives you an idea.